Piezoelectric vibration sensor

ABSTRACT

A sensor unit for picking up mechanical vibrations, sound and ultrasound has at least one piezoelectric foil strip (piezo strip) as a sensor element. The piezo strip has signal wires attached thereto for transporting out electrical signals representing vibration, sound or ultrasound that have been picked up. The piezo strip is, at two opposite ends, attached to flat support parts, and at least one engagement strip of for instance plastic material is attached in the same support parts to extend in curved-out fashion along the piezo strip, thereby to provide at least one space between the strips. Several sensor units can be mounted together in a frame to constitute a sheet with a sensor matrix.

BACKGROUND OF THE INVENTION

The present invention relates in general to sensing of mechanicalvibrations, possibly in the form of sound or ultrasound, by means of oneor several sensor units having a piezoelectric foil as asignal-delivering element. More particularly, the invention relates to asensor unit for picking up mechanical vibrations, sound, and ultrasound.In further aspects, the invention relates to a vibration detector arraywith a plurality of sensor units. Finally, the invention relates to usesof such vibration detector arrays.

Particularly within the art of auscultation, i.e. the art concerninglistening for sounds generated in living bodies, for instance heartsounds, many different sensor types have been developed for use by e.g.a doctor, for examination purposes. In this connection, reference ismade to previous patent publications regarding auscultation and sensortechnology belonging to the owner of rights to the present invention,see for instance Norwegian patents 300250, 304870 and 306926. Thepresent invention is primarily directed to this type of examination, andaims particularly at being able to prepare a mapping of an area in aliving body on the basis of a matrix investigation. In other words,sound/vibration picked up by plural sensors, is converted to separatesignals to be led into a computer that provides systematizing of thesound/ultrasound image in order to prepare a composite mapping of thesound that is received from a large area, for instance an area of theback of a person, or a chest area.

But, in addition to the above, there are also industrial areas of use.For instance, it is possible to undertake a vibration analysis ofunderlying structures by means of a sensor matrix laid down on a metalsurface of a machine construction or similar device.

However, the invention does not concern signal processing or algorithmsin connection therewith, but deals with special sensor elements intendedto be included in larger sensor groups or arrays, possibly sensormatrices, and the composition of such sensor groups.

SUMMARY OF THE INVENTION

Hence, in a first aspect of the present invention, there is provided asensor unit for picking up mechanical vibrations, sound and ultrasound,having at least one piezoelectric foil strip (piezo strip) as a sensorelement. The piezo strip has signal wires attached for exportingelectric signals representing vibration, sound or ultrasound beingpicked up. The sensor unit in accordance with the invention ischaracterized in that the piezo strip is, at two opposite ends, held infiat support parts, and in that at least one engagement strip forreceiving vibrations and propagating them to said piezo strip is held inthe same support parts so as to extend in a curved manner along thepiezo strip, thereby to provide at least one space between the strips.

In a preferred embodiment of the invention, the support parts areseparate support pieces having holding details for the strips, forinstance pockets.

In another preferred embodiment, the sensor unit comprises two suchengagement strips, one outside each flat side of the piezo strip.

The further (engagement) strip/strips may be a little stiff, and willthen automatically tend to stretch the piezo strip. Also, the engagementstrip/strips may be held loosely in at least one of the support parts,by being inserted into a pocket.

In an important embodiment of the invention, the space between the piezostrip and the engagement strip is occupied by a substance with theability to transfer pressure, for instance a silicon substance. Thepiezo strip and the engagement strip are substantially symmetricallycurved outwards centrally to bound the substance.

In another embodiment of the invention, the support parts areconstituted by welding rims for a bubble consisting of two semi-ovoidfoil pieces, and the at least one engagement strip constitutes at leastone of the two foil pieces. The piezo strip may then be arrangedoutstretched in the space right in between the two foil pieces. Inaddition, the piezo strip may be attached along the whole welding rim,thereby to constitute a boundary between two closed spaces. At least oneof the two closed spaces may be filled by a substance having the abilityto transfer a pressure. One of the substances may have a hardness valueof the same magnitude as body tissue in an area in and under the skin ina topical listening area on a human body or animal body.

In another aspect of the invention there is, as mentioned in theintroduction, a vibration detector array comprising a number of sensorunits arranged in a substantially planar a×b-matrix with a units alongone direction and b units along a perpendicular direction in the plane,and with separate signal wires going out from each separate sensor unit.The vibration detector array according to this aspect of the inventionis characterized in that each sensor unit is constructed such as statedin any one of the above embodiments that do not relate to a bubbleshape, and that each sensor unit is attached in a common surroundingframe.

The frame may then be designed with b parallel openings, in whichopenings of the sensor units are mounted by means of a common supportpiece constituting a boundary edge for each opening, for one end of thea sensor units, while the other end of each one of the a sensor unitshangs freely in the opening.

In accordance with a further aspect of the invention, there is avibration detector array comprising a number of sensor units arranged ina regular and substantially planar configuration, and with separatesignal wires going out from each separate sensor unit. The vibrationdetector array according to this aspect of the invention ischaracterized in that each sensor unit is such as stated in one of theabove mentioned embodiments with a bubble design, and that a pluralityof bubbles are arranged in close juxtaposition, with welding rims thatare common for neighbor bubbles.

In accordance with one further aspect, the present invention comprises ause of at least one vibration detector array such as stated in theprevious sections, as a part of a piece of clothing that can be worn bya person for carrying out a mapping auscultation examination.

A further aspect of the invention comprises a use of at least onevibration detector array such as stated in the previous sections, as amat or a belt for industrial vibration pickup analysis, the mat/beltbeing equipped with suitable means for attachment.

A BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention shall be described in closer detail bygoing through some exemplary embodiments, and in this connectionreference is made to the appended drawings, of which:

FIG. 1 is an elevation view showing a basic embodiment of a sensor unitin accordance with the present invention, as seen laterally in crosssection with a piezo-foil strip and a plastic strip,

FIG. 2 shows, in a corresponding manner to FIG. 1, an embodiment havinga central piezo-foil strip and plastic strips on both sides of thepiezo-foil,

FIG. 3 shows, in a corresponding manner to FIGS. 1 and 2, an embodimentwith a plastic foil strip together with an outwardly curved piezo-foilstrip and a silicone substance between the foils,

FIG. 4 shows, in a top view, an example of the appearance of a sensorunit in accordance with one of FIGS. 1 and 2,

FIG. 5 shows an example of the attachment of strip ends in an end piecefor a sensor unit, enlarged and in a view from the side,

FIG. 6 shows how a number of sensor units may be arranged in matrixshape in a frame,

FIGS. 7 a and b show an alternative manner of attachment for sensorunits in a frame,

FIG. 8 shows an embodiment with a sensor unit of a bubble type, with apiezo-foil strip centrally arranged and air inside the bubble, in aperspective view and with one half of the bubble cut away,

FIG. 9 shows, in the same manner as FIG. 8, an alternative bubbleembodiment with a substance on one side of the piezo-foil strip and airon the other side,

FIG. 10 shows another bubble alternative with substances on both sidesof the piezo-foil strip,

FIGS. 11 a and b show sheets containing bubble collections,

FIG. 12 shows, in a sectional side view, a bubble sheet with extraequipment in the form of an inflatable sound barrier pad and externalcladding sheets,

FIG. 13 shows, sketch-like, how bubble sheets or sensor unit matrixframes can be arranged in pieces of clothing, and

FIG. 14 shows a belt-shaped sensor mat for industrial applications.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a first and basic embodiment of the invention, namelya sensor unit with a piezoelectric foil strip 1 that is attached at bothends to fiat support parts 3 that constitute end pieces. An engagementstrip 2 extends along piezo strip 1, and in the embodiment shown, strip2 is a lithe longer than piezo strip 1, so that the center of strip 2bulges a little outward. Strip 2 can also be fixed at both ends to thesupport parts 3, but it may equally well simply be inserted into apocket (6, see FIGS. 4 and 5) in the support parts, at both ends or atone end.

The piezo-foil strip 1 may for instance have external measurements of6×1 cm², these values not constituting any limitation, and the foilitself may be delivered off the shelf. A typical foil thickness may bein the range 28-56 μm, however these values shall not constitute anylimitation.

The engagement strip 2 may also be a thin foil, preferably a foil thatis a little stiff, unless the space between the two strips 1, 2 isoccupied by a substance (see below). Such a foil strip 2 can be made ofa plastic material, possibly a rubber material, a thermo foil, a textilematerial or another material.

The mode of operation for the sensor unit is that the engagement strip 2is brought into engagement with the surface of a body to be listened to,and sound/vibrations in the body may then propagate to the piezo-foil 1in two ways, depending on for example the stiffness of the engagementstrip 2. Firstly, sound/vibration may propagate right through theengagement strip 2 to reach piezo strip 1 directly. Secondly, vibrationsthat are transmitted to a stiff engagement strip 2, may cause avibrating tension in piezo strip 1 via the support parts 3, whichsupport parts are then vibrated toward each other and apart by strip 2.For instance, when listening to machine parts, it is possible to use arather stiff and curved aluminium plate of e.g. 1 mm thickness asengagement strip 2 in the sensor unit. (Numerical values and materialspecifications are stated only as non-limiting examples.)

Signal wires from piezo strip 1, i.e. one wire from each side of thepiezo-foil, lead out through a support part 3. In the embodiment shown,the support parts 3 are relatively stiff, flat and made from anelectrically insulating material, for instance a casting material likeplastic (for example polyurethane), glue, stiff cardboard, gore-tex,plaster/tape, or possibly two metal layers with insulationthere-between. Piezo-foil strip 1 is attached to each support part 3 byclenching, gluing or attaching in a similar manner, two flat parts ofthe support part, with the piezo-foil pinched therebetween.

FIG. 2 illustrates a second embodiment of the sensor unit in accordancewith the invention. The only difference relative to the embodiment shownin FIG. 1, is the provision of an extra engagement strip 2′ on the otherside of piezo strip 1, in such a manner that the configuration becomessymmetrical if strips 2 and 2′ are made from the same material and havethe same length. However, this embodiment shall not be limited to asymmetrical construction. With a symmetrical configuration, however, anyone of the two sides of the sensor unit can be chosen for engagementwith the body to be listened to. Piezo strip 1 can also be tensioned byapplying a pressure to the outer strip (e.g. 2′) that does not engagethe body to be listened to.

FIG. 3 illustrates a somewhat different variant of the sensor unit inaccordance with the invention. In this case, a piezoelectric foil strip1′ and an engagement foil strip 2 are both fixedly fastened in supportparts 3, and in between them a silicone substance 4 has been loaded, tokeep the two foils 1′, 2 apart such as shown in the drawing. Thesilicone substance can be replaced by some other substance having atleast an equally high viscosity and similar pressure transmissioncharacteristics, i.e. a substance that is equally solid or an even moresolid substance.

It must be noted that in the embodiments as shown in FIGS. 1, 2 and 3,the sensor units are, as a starting point, open at the sides (i.e., in adirection out of and into the drawing sheet). This means that in theembodiment of FIG. 3, the substance 4 must be sufficiently solid not toflow out at the sides of its own accord. (In the embodiments in FIGS. 1and 2, there is only air between the strips.) But the embodiments ofFIGS. 2 and 3 will also lead in a natural manner to closed embodiments,i.e. bubble-shaped embodiments that will be discussed below.

FIG. 4 illustrates a sensor unit in accordance with FIG. 1 or FIG. 2 ina view from above, and the same reference numerals are still used forthe same elements. Reference numeral 5 designates signal wires leadingout from the piezo strip, reference numeral 6 designates insertionpockets for engagement strips 2, 2′, and fastening areas for piezo strip1 are designated by reference numeral 7.

FIG. 5 shows, enlarged and in partial elevation, a support part 3 withan insertion pocket 6, a fastening area 7 and engagement strips 2 and 2′entering pocket 6. In this embodiment, two piezo strips 1 enter supportpart 3 and are fixed in area 7. The purpose of using several piezostrips at the same time is to change the capacitance and to obtain othersignal strength values.

As mentioned in the introduction, a main purpose of the sensor unit inaccordance with the invention is to constitute part of larger groups ofsuch units. FIG. 6 shows one example among many possible ones, both withregard to number and array structure, of an arrangement of sensor unitsin a two-dimensional array 10, for use in computer-assistedauscultation, with sound recording from a body through a large surfacearea. In the example, a frame 8 appears, in which frame there arearranged thirty sensor units in accordance with one of the previouslymentioned embodiments, and the sensor units are arranged in a regular5×6 matrix array. In the embodiment shown, each sensor unit has an endwith a separate (individual) support part 3 “hanging freely” in an openspace in the frame, while all six sensor units in one such open spaceare attached to one and the same elongated support part 3′ thatconstitutes a cross-arm internally in frame 8. Hence, frame 8 containsfour internal cross-arms 3′ of this type, and additionally, the lowerframe edge is also a common support part 3′ of this type for six sensorunits. It appears also that signal wire pairs 5 a, 5 b, 5 c exit alongthe support parts 3′, i.e. one pair from every single sensor unit.

Such a sensor array sheet 10 can be laid engagingly toward a surface tobe listened to, or attached thereto, or it can be sewn or welded into agarment or a garment part that is suitable to be slipped onto orattached to the body of a patient for auscultation examination, see FIG.13.

FIGS. 7 a and 7 b illustrates an embodiment that is a little differentfrom the embodiment shown in FIG. 6, namely in the fact that each sensorunit is attached fixedly to frame 8′ at both ends (i.e., the supportparts 3′ are in this case common “everywhere” to six sensor unitsarranged in a row). Thus, in FIG. 7 a, one such row of sensor units isshown in accordance with one of the previously mentioned embodiments,but in this case the sensor units are arranged with common support parts3′ at both sides. For the rest, the reference numerals in FIG. 7 adesignate elements in a corresponding manner as previously. FIG. 7 billustrates a complete frame 8′ merely with indications (actuallyinsertion pockets 6) of seating locations for single sensor units in theframe. Hence, in this case, the piezo strip of every sensor unit will beattached fixedly to the frame at both ends.

In the embodiment appearing in FIG. 6, i.e. with sensor units that arefree at one end, an outer pressure will be necessary to provide goodsignals from the listening object. In comparison, the embodiment shownin FIG. 7 provides a frame-bound support of single sensors, and it canbe used with precision for monitoring a certain area, since the sides ofthe frame represent the pressure (i.e. through the selected pressure ofthe frame sides against the surface of the listening object when theframe is attached/fastened).

As previously mentioned in connection with FIGS. 2 and 3, an alternativeembodiment is of a type that is closed laterally. FIGS. 8, 9 and 10illustrate alternative but related embodiments of sensor units inaccordance with the invention, which sensor unit embodiments aresuitable to constitute parts of larger “bubble sheets”. A sensor unit ofthe simplest bubble type appears in FIG. 8 (i.e., FIG. 8 shows a sectionof a bubble in a perspective view). The bubble consists of two distended(inflated) bubble halves 12 meeting along a welding rim 26 that definesan oval/elliptical opening in a planar sheet 11. A piezo strip 1 of thesame type as mentioned previously, is attached at its two ends inwelding rim areas 13 in sheet 11, and extends across the oval/ellipticalopening in the sheet. Hence, above and below the opening in sheet 11,which opening contains a cross-over piezo strip 1, curved strips 12 risein the form of bubble halves delimiting a closed space surrounding thepiezo strip 1. Inside the space there is air or possibly some other gas.

In FIG. 9, a substance 9 has been brought in at one side of piezo strip1 in a bubble shaped similarly to that shown in FIG. 8, and in a similarmanner to that shown in FIG. 3. Further, in FIG. 10, substances 9, 9′have been laid in at both sides of the piezo strip. The substances maybe silicone substance, a gel, rubber or a metallic material. (In thelast mentioned case, it must be mentioned that it is not possible to usean electrically conducting substance on both sides of the piezo strip,because of the possibly of short-circuiting the piezo foil.)

As previously mentioned, the substances should not be too “thin” (i.e.,they should be sufficiently solid), so that they will stay at respectivesides of the piezo strip even though the strip does not divide thebubble space in two closed halves. It should be noted, however, that thepiezo strip may be shaped with a lateral extension in the central part,in order to better cover the sheet opening (see the shape in FIG. 11 b).The central area of the piezo strip must be free, in order to obtain agood signal from the strip. Therefore, attachment of the strip 1 to theside edges can normally not be made without at the same time havingprecise control over the elastic characteristics of the bubble wall. Butin such an embodiment, it will be possible to separate the twosubstances completely, and then it will be possible to also use more“thin” substances, possibly also different gases at each side of thepiezo strip.

FIG. 11 a illustrates an assembly of single bubble sensor units in asheet 11 of larger size, however not larger than two by three bubbles.FIG. 11 b shows an equally large bubble sheet 11, in which the separatepiezo strips 1″ have an extended central part with a side edge 14 thatcurves out toward the side edge of the opening/the bubble wall. But asmall clearance still remains between strip 1″ and the bubble wall inthis case.

FIG. 13 illustrates two examples of garments or garment-like units, intowhich unit bubble sheets or sensor matrix sheets can be built. A person21 in the figure wears in an upper position a vest 22 having a bubblesheet or a sensor matrix sheet 23 attached therein, and anotherembodiment in the form of a thigh bandage 24 is also equipped with amatrix 25 of sensor units. This may be a matter of auscultationregarding heart or lung function using the vest 22, and of listening toan artery with the bandage 24. A gathering cable (not shown) will carrysignals to a (not shown) computer that interprets the signals andgenerates a suitable display. Simpler types of garments can be ofinterest. It is for instance possible to provide mat or belt shapedgarments that have a sensor bubble or sensor matrix sheet across asubstantial part of their surface. Such mat/belt shaped garments maythen have attachment means in the form of elastic areas with velcro.

FIG. 12 shows, in a sectional view through a bubble sheet, various extraequipment that is possible and that may be of interest in connectionwith auscultation examinations. Reference numeral 20 designates thetopical listening object. A sound-transparent material, for instancesilk fabric, synthetic fabric, or cloth, is shown by reference numeral15, and forms a surface between the actual bubble sheet 11 and theobject 20. On the outside (underside) of the bubbles,inflatable/fillable pads or fields 18 are arranged, with a valve 19. Anumber of bubbles can be covered by such a pad, which has for itspurpose to provide shape adaptation against a body or similar. Referencenumeral 17 designates a noise barrier layer. This may relate toscreening against incident electromagnetic radiation, and electricallyconductive material is then used. It may also be of interest to screenagainst external sounds/vibrations, and then a sound-absorbing substancewill be used, for instance felt or similar. It may be of interest to useboth types of screening at the same time. Finally, layer 16 constitutesan outer cover, which may be related to design, and which may consist offor instance a textile, oil skin, goretex or other material.

As regards types of substances that should possibly be used in bubblesheets, an embodiment of interest would be that the bubbles in the halfthat faces e.g. a body part to be listened to, contains a substancehaving hardness (i.e. “Shore”-number) adapted to the hardness of thebody tissue in and just under the skin, in order to obtain adaptationwith regard to acoustic impedance. In the outer half of the bubbles, airmight be chosen. Such a configuration makes it easier to separate sound(noise) received from the surroundings, from the signals of interest.

FIG. 14 illustrates an example of an industrial “belt” or “mat”embodiment of a sensor matrix sheet or bubble sheet, or actually abubble sheet which has been drawn in the shape of a belt 27. Belt 27 isequipped with an attachment device 28 which in this case is an elasticarea with velcro, but an attachment device in the form of bands, hooks,buttons etc. can be provided in topical cases. The belt/mat shall bestrapped down to a construction part in order to make it possible tolisten through an engagement surface, with regard to sound/vibrationanalysis of underlying structures.

Finally, it should also be mentioned that the possibility exists toprovide sensor matrix sheets and bubble sheets with a furthercombination effect with regard to auscultation examination of a patient.It will actually be possible to combine electrodes for engagementdirectly against the skin surface of a patient, for instance on 5-6special sensor elements among 40-50 elements in a sheet, in order tomake a simultaneous ECG examination. This means then that, as previouslymentioned, the strip 2 in these special sensor units may be of metal,and connected in a special manner for transporting out electricalsignals received from the body. In the case with bubbles, the specialsensor bubbles intended for the ECG, may then have metallization orthrough electrodes for contacting the skin. In the previously mentionedcase with an electrically conductive substance in one half of a bubble,further transmission of a signal may then possibly be effected throughthis conductive substance, or separate wiring may be arranged.

1. A sensor unit for picking up mechanical vibrations, sounds, andultrasound from a surface of a body, comprising: a piezoelectric foilstrip defining a sensor element, said piezoelectric strip having signalwires attached thereto for transmitting electrical signals representingthe vibrations, sounds, or ultrasound to be picked up; flat supportparts for holding only opposite ends of said piezoelectric strip; and anengagement strip for engaging the surface of the body to receivevibrations therefrom, and for propagating the vibrations to saidpiezoelectric strip, said engagement strip being held in said supportparts so as to extend in a curved manner along said piezoelectric stripand define a space between said piezoelectric strip and said engagementstrip.
 2. The sensor unit of claim 1, wherein said support parts areseparate support pieces having holding pockets receiving one of saidopposite ends of said piezoelectric strip.
 3. The sensor unit of claim2, wherein said engagement strip is stiff and curved so as to tensionsaid piezoelectric strip.
 4. A vibration detector array comprising: aplurality of sensor units arranged in a substantially planar A by Bmatrix with A units arranged along a first direction, and B units in asecond direction perpendicular with respect to the first direction andwithin the same plane, each of said sensor units comprising a sensorunit as recited in claim 2; separate signal wires leading out from eachof said plurality of separate sensor units; and a frame to which each ofsaid plurality of sensor units is attached.
 5. The vibration detectorarray of claim 4, wherein said frame has B parallel openings in which afirst end of each of A sensor units is mounted by a common support piececorresponding to one of said support parts, said common support piecedefining a boundary edge for each of said B parallel openings, a secondend of each of said A sensor units hanging freely.
 6. A method of usinga vibration detector, comprising: incorporating said vibration detectorarray as recited in claim 4 into a garment; and having a person wear thegarment for carrying out a surveying auscultation examination of theperson.
 7. A method of using a vibration detector, comprising:incorporating said vibration detector array as recited in claim 4 into abelt having an attachment device; and attaching the belt to an objectfor industrial vibration pickup analysis of the object.
 8. The sensorunit of claim 1, wherein said engagement strip constitutes a firstengagement strip, further comprising a second engagement strip, saidfirst engagement strip and said second engagement strip being located onopposite sides of said piezoelectric strip.
 9. The sensor unit of claim8, wherein each of said first engagement strip and said secondengagement strip is stiff and curved so as to tension said piezoelectricstrip.
 10. A vibration detector array comprising: a plurality of sensorunits arranged in a substantially planar A by B matrix with A unitsarranged along a first direction, and B units in a second directionperpendicular with respect to the first direction and within the sameplane, each of said sensor units comprising a sensor unit as recited inclaim 8; separate signal wires leading out from each of said pluralityof separate sensor units; and a frame to which each of said plurality ofsensor units is attached.
 11. The sensor unit of claim 2, wherein saidengagement strip is stiff and curved so as to tension said piezoelectricstrip.
 12. The sensor unit of claim 11, wherein said engagement strip isloosely attached to one of said support parts by being inserted into apocket of said one of said support parts.
 13. The sensor unit of claim1, wherein the space between said piezoelectric strip and saidengagement strip is filled with a substance operable to transferpressure, said piezoelectric strip and said engagement strip havingcentral areas substantially symmetrically outwardly curved so as tomaintain said substance in place.
 14. The sensor unit of claim 1,wherein said support parts comprise welding rims, said engagement stripcomprises a first semi-ovoid foil piece, further comprising a secondsemi-ovoid foil piece, said first semi-ovoid foil piece and said secondsemi-ovoid foil piece having opposite ends held by said welding rims soas to define a bubble shape.
 15. A vibration detector array comprising:a plurality of sensor units arranged in a substantially planarconfiguration, each respective sensor unit having separate signal wiresleading out therefrom, each of said sensor units comprising a sensorunit as recited in claim 14, said sensor units being arranged in closejuxtaposition so that adjacent sensor units share a common welding rim.16. The sensor unit of claim 14, wherein said piezoelectric strip isstretched in a space defined between said first semi-ovoid foil pieceand said second semi-ovoid foil piece, and is located midway betweensaid first semi-ovoid foil piece and said second semi-ovoid foil piece.17. The sensor unit of claim 16, wherein at least one of a space definedbetween said first semi-ovoid foil piece and said piezoelectric stripand a space defined between said second semi-ovoid foil piece and saidpiezoelectric strip is filled with a substance operable to transferpressure.
 18. The sensor unit of claim 17, wherein said substance has ahardness value of the same magnitude as body tissue in an area in andunder skin of a topical listening area of a human body or animal body.19. The sensor unit of claim 1, wherein only opposite ends of both saidpiezoelectric strip and said engagement strip are fixed to said supportparts such that each opposite elongated side of said sensor unit isopen, further comprising a viscous silicone substance between saidpiezoelectric strip and said engagement strip.
 20. A vibration detectiondevice comprising: a garment to be worn by a person; and a vibrationdetection array incorporated into said garment, said array including: aplurality of separate sensor units arranged in a substantially planarmanner, each of said sensor units comprising a sensor unit as recited inclaim 1; separate signal wires leading out from each of said pluralityof separate sensor units; and a frame to which each of said plurality ofsensor units is attached.